Table 4.

Main electrophysiological parameters of the different GABA_A receptor subtypes in standard ionic conditions (subunits expressed in Xenopus oocytes)

GABAA receptor subtype	GABA EC50 (µM)	Hill coefficient
α1β1γ1	25 [163] 41 [164] 75 [166]
α1β1γ2	9.8 [170] (γ2S splice variant) 19.9 [126] (γ2S splice variant)	1.36 [126] (γ2S splice variant)
α1β1δ	4.9 [170]
α1β1ε	4.0 [126]	0.85 [126]
α1β2γ2	41 [153] 16 [132] (γ2L splice variant) 45.8 [47, 173, 174] 34 [97] (γ2L splice variant) 55 [175] 20 [155] 20 [163] 4.61 [176] (γ2L splice variant)	1.39 [153] 1.59 [174] 1.57 [47, 173] 1.38 [97] (γ2L splice variant) 1.4 [175] 1.38 [176] (γ2L splice variant)
α1β3γ2	8 [163]
α2β1γ1	39.8 [183]
α2β1γ2	30.6 [183]
α3β1γ1	114 [163]
α3β1γ2	240 [154] 208 [163] 200 [186] (γ2S splice variant) 98 [164]
α3β1γ3	32 [163]
α3β1ε	2.3 [186]
α3β1θ	81 [186]
α3β2γ2	487 [154] 11 [163]
α3β3γ2	28 [163]
α5β1γ2	17 [154] 15 [163]
α5β2γ2	14 [154]
α5β3γ1	24 [163]
α5β3γ2	3 [163] (γ2L splice variant)
α5β3γ3	2 [163]
α6β2γ2	6.7 [153] 1.6 [155]	0.82 [153]
ρ1	0.81 [106]	2.83 [106]
ρ2	1.19 [162]	2.17 [162]

Roman: rat subunits; bold: human subunits; italics: bovine subunits; bold italics: mouse subunits. The Hill coefficient, GABA EC50, main conductance state and characteristic times of activation, deactivation and desensitization of the most abundant subtypes in vivo, i.e. ternary subtypes and ρ homopentamers, are presented. Information on other subtypes can be found in [13, 103, 112, 114, 116, 123, 125, 130, 146, 152–157, 176, 180, 182, 191, 192]